/*
  js基本数据类型：string number boolean null undefined symbol bigInt
    symbol: 创建的值是唯一的，作为对象属性是唯一的，不会覆盖
    bigInt: 长整形（为了解决number类型在较大数据运行精度会有问题）
*/

let a: number = 1;
a = 3;
// a = "string"; // 报错
a = undefined;
a = null;
const b: string = "111";
const c: boolean = true;
let d: null = null;
d = undefined;
let e: undefined = undefined;
e = null;
const f: symbol = Symbol();
const g: bigint = 1111n;
